US20060072680A1 - Method of space-time encoding and decoding for frequency selective fading channel - Google Patents

Method of space-time encoding and decoding for frequency selective fading channel Download PDF

Info

Publication number
US20060072680A1
US20060072680A1 US10/518,426 US51842605A US2006072680A1 US 20060072680 A1 US20060072680 A1 US 20060072680A1 US 51842605 A US51842605 A US 51842605A US 2006072680 A1 US2006072680 A1 US 2006072680A1
Authority
US
United States
Prior art keywords
interference
decoding
diversity
space
encoding
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
US10/518,426
Other versions
US7606318B2 (en
Inventor
Yingmin Wang
Xiaolong Ran
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Datang Mobile Communications Equipment Co Ltd
Original Assignee
Datang Mobile Communications Equipment Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Datang Mobile Communications Equipment Co Ltd filed Critical Datang Mobile Communications Equipment Co Ltd
Assigned to DA TANG MOBILE COMMUNICATIONS EQUIPMENT CO., LTD. reassignment DA TANG MOBILE COMMUNICATIONS EQUIPMENT CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: RAN, XIAOLONG, WANG, YINGMIN
Publication of US20060072680A1 publication Critical patent/US20060072680A1/en
Application granted granted Critical
Publication of US7606318B2 publication Critical patent/US7606318B2/en
Assigned to CHINA ACADEMY OF TELECOMMUNICATIONS TECHNOLOGY reassignment CHINA ACADEMY OF TELECOMMUNICATIONS TECHNOLOGY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: DA TANG MOBILE COMMUNICATIONS EQUIPMENT CO., LTD.
Assigned to DATANG MOBILE COMMUNICATIONS EQUIPMENT CO., LTD. reassignment DATANG MOBILE COMMUNICATIONS EQUIPMENT CO., LTD. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: CHINA ACADEMY OF TELECOMMUNICATIONS TECHNOLOGY
Active legal-status Critical Current
Adjusted expiration legal-status Critical

Links

Images

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00Arrangements for detecting or preventing errors in the information received
    • H04L1/02Arrangements for detecting or preventing errors in the information received by diversity reception
    • H04L1/06Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
    • H04L1/0618Space-time coding
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69Spread spectrum techniques
    • H04B1/707Spread spectrum techniques using direct sequence modulation
    • H04B1/7097Interference-related aspects
    • H04B1/7103Interference-related aspects the interference being multiple access interference
    • H04B1/7105Joint detection techniques, e.g. linear detectors
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B2201/00Indexing scheme relating to details of transmission systems not covered by a single group of H04B3/00 - H04B13/00
    • H04B2201/69Orthogonal indexing scheme relating to spread spectrum techniques in general
    • H04B2201/707Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation
    • H04B2201/70707Efficiency-related aspects

Definitions

  • the invention relates to mobile communication technology, more particularly to a method of space-time encoding and decoding for a frequency selective fading channel.
  • Space-time encoding is one of the important methods that can raise performance of a wireless communication system effectively.
  • There are two branches of the space-time encoding one is layered space-time encoding and the other is space-time encoding based on transmitting diversity.
  • the space-time encoding based on transmitting diversity can be further divided into two kinds: space-time block encoding and space-time trellis encoding.
  • the prior space-time encoding and decoding schemes are designed based on a flat fading channel.
  • the schemes are used for a frequency selective fading channel, the performance becomes worse obviously, and it is too complex to implement when improving performance of the algorithm.
  • ISI Inter-Symbol Interference
  • MAI Multiple Access Interference
  • 3GPP-TDD Time Division Duplex
  • 3GPP-FDD Frequency Division Duplex
  • the space-time transmission diversity (STTD) scheme is discarded in 3GPP-TDD v4.3 and space code transmission diversity (SCTD) scheme is applied.
  • SCTD space code transmission diversity
  • ST-OFDM space-time—orthogonal frequency division multiplexing
  • the space-time encoding and decoding method is important to improve performance of a wireless communication system.
  • a symbol or a string of symbols are used as a processing unit for encoding and decoding, but under the condition of a frequency selective fading channel, improvement of performance is limited by the calculation complexity.
  • An object of the invention is to design a space-time encoding and decoding method that is suitable to the frequency selective fading channel to obtain better performance with small amount of calculation complexity.
  • a space-time encoding and decoding method for a frequency selective fading channel comprises:
  • Two diversity signals in step A may be transmitted through two diversity beams of one smart antenna respectively and simultaneously.
  • the method may further comprise the step of predefining number of iteration times to determine execution times from step C to step D and from step D to step C again.
  • the method of the invention is a new space-time encoding and decoding method that is suitable to a frequency selective fading channel.
  • the method takes an independent data field as a processing unit, and the decoding applies an iteration method based on joint detection and interference counteraction.
  • joint detection only affect to diversity signal from multipath interference and multi-user interference is taken into account, and then interference counteraction is implemented based on the joint detection result to remove interference between diversity signals.
  • the invention provides a simple and effective solution for space-time encoding and decoding on a frequency selective fading channel.
  • FIG. 1 is a schematic diagram illustrating a data structure for time-slot CDMA burst data.
  • FIG. 2 shows the input and output of a space-time encoder when taking a data field as a processing unit.
  • FIG. 3 is a flowchart illustrating the simplified decoding procedure of the invention.
  • the ISI exists between neighbor symbols. Therefore, in a general space-time encoding method, there is not only interference between diversity signals, but also interference between neighbor encoding units and interference between neighbor encoding blocks. If the interference were neglected, the communication performance would be worse; and if the interference were considered, the calculation complexity would be increased greatly.
  • An independent data block is taken as the processing unit in the encoding and decoding method according to the present invention, so the interference between neighbor encoding units and neighbor encoding blocks does not exist, which simplifies the signal detection and decoding processing.
  • This processing method is similar or compatible to the processing methods in which space-time encoding processing is not employed to a great extent. Many processing schemes for counteracting ISI and MAI can be used in the space-time encoding situation with small amount of change.
  • FIG. 1 shows data structure of a time-slot CDMA burst data in the 3GPP-TDD system. It can be seen from FIG. 1 that in parallel K burst data of a multi-user or multi-channel, each time-slot includes two data fields (or referred as data blocks): DATA FIELD 1 and DATA FIELD 2 , and there is a midamble between these two data fields. So these two data fields are independent and there is no mutual interference between them.
  • the end of a time slot is a guard period (GP). Every data field has N symbols, and every symbol is consisted of Q chips.
  • GP guard period
  • an independent data field is used as a processing unit for encoding, and at the receiving end the decoding also takes a data field as a processing unit. It is simple when this method is used in double diversity (theoretically it can be used in the multiple diversity, but the complexity is increased and therefore it is not practicable). Therefore, the encoding and decoding method according to the present invention can be employed with small amount of change for the signal structure and processing method. Furthermore, since the two data fields are independent, and there is no interference between them, the detection and decoding method can be simplified and improved, and better detection performance can be obtained with a small amount of calculation volume or a small quantity of iterative times.
  • FIG. 2 shows a space-time encoder 20 taking a data field as a processing unit.
  • Input data of the encoder 20 i.e., information data vector d in a time slot
  • d [d T (1)d T (2)] T
  • d(1) and d(2) are two independent data fields, and in a 3GPP-TDD system they can be two data fields in one time slot
  • T denotes a transpose operation.
  • the data which has been encoded by the encoder 20 is [d T (1)d T (2)] T and [ ⁇ d* T (2)d* T (1)] T , wherein * represents conjugate.
  • the two generated data vectors can be transmitted simultaneously by two different conventional diversity antennas: diversity antenna 1 and diversity antenna 2 , or by two different diversity beams of one smart antenna: smart antenna diversity beam 1 and smart antenna diversity beam 2 .
  • the diversity antenna 1 (or diversity beam 1 ) transmits data vector [d T (1)d T (2)] T
  • the diversity antenna 2 (or diversity beam 2 ) transmits data vector [ ⁇ d* T (2)d* T (1)] T simultaneously, thereby the space-time encoding is realized.
  • the input data [d T (1)d T (2)] T is encoded by conventional space-time diversity orthogonal encoding method, and two output data vectors: [d T (1)d T (2)] T and [ ⁇ d T (2)d* T (1)] T are obtained and transmitted via two diversity antennas simultaneously and respectively.
  • the detection and decoding method for space-time encoding mode which takes a data field as a processing unit will be described, i.e. the detection and decoding scheme corresponding to the designed data field encoding scheme will be described.
  • the original detection and decoding method it is called the original detection and decoding method.
  • r 1 and r 2 represent the sample values of two data fields received at the terminal, and there is no interference between r 1 and r 2 even on a frequency selective fading channel.
  • n i is the noise vector of the ith data field
  • a i is the system matrix of the signal transmission between the ith transmitting antenna and receiving antenna, and the system matrix is determined by the channel pulse response and the user transmission waveform.
  • a * T ⁇ A [ A 1 * ⁇ T ⁇ A 1 + ( A 2 * ⁇ T ⁇ A 2 ) * ( A 1 * ⁇ T ⁇ A 2 ) T - A 1 * ⁇ T ⁇ A 2 ( ( A 1 * ⁇ T ⁇ A 2 ) T - A 1 * T ⁇ A 2 ) * ⁇ T ( A 1 * ⁇ T ⁇ A 1 + ( A 2 * ⁇ T ⁇ A 2 ) * ) * ] ( 5 )
  • the matrix A is not an orthogonal matrix under the condition of frequency selective fading channel, so the performance will become worse if a match filter is applied.
  • the optimized linear joint detection scheme is provided.
  • the dimension of matrix B is 2NK ⁇ 2NK, so the calculation complexity of formula (6) is far greater than that under the situation of no space-time encoding. Therefore, the object of simplifying processing and reducing calculation volume proposed in the invention cannot be realized with the original joint detection algorithm.
  • the invention provides a simplified decoding procedure having a characteristic of a small amount of calculation volume.
  • the simplified algorithm is an iterative algorithm. It is divided into two steps. In the first step, only multi-path interference and multi-user interference to every diversity signal is taken into account, and the upper right block of the formula (5) ( A 1 * T A 2 T ⁇ A 1 * T A 2 ) and the lower left block of the formula (5) ( A 1 * T A 2 T ⁇ A 1 * T A 2 * T ) are set to null, then the equation (6) is calculated. In the second step, interference is counteracted with the result of the first step to remove interference between diversity signals. The procedure can be done by multiple iterations.
  • FIG. 3 is a flowchart of the simplified decoding procedure of the invention.
  • Step 31 the terminal receives data.
  • Step 32 mutual interference between diversity signals caused by their non-orthogonality is neglected, upper right block and lower left block of formula (5) are set to be null (they are null under the condition of a flat fading channel).
  • Formula (8) gives the result of simplified joint detection.
  • the matrix B S in formula (8) is given by formula (9):
  • B S ⁇ I MF A 1 * ⁇ T ⁇ A 1 + ( A 2 * ⁇ T ⁇ A 2 ) * ZF - BLE A 1 * ⁇ T ⁇ A 1 + ( A 2 * ⁇ T ⁇ A 2 ) * + ⁇ 2 ⁇ I MMSE - BLE ( 9 )
  • ⁇ 2 is the noise power
  • I is the identity matrix.
  • Calculating matrix B S also has three ways: match filter MF, zero-forcing block equalization ZF-BLE and minimum mean-square-error block equalization MMSE ⁇ BLE.
  • Step 34 whether the number of iteration times is equal to or greater than the predefined number M is judged.
  • M is set at 1 or 2.
  • Step 35 when the number of iteration times is equal to or greater than the predefined number M, the calculation result of formula (8) is outputted as the decoding result directly.
  • Step 36 when the number of iteration times is less than the predefined number M, the calculation result of formula (8) is used to implement interference counteraction so as to remove interference between diversity signals, that is, an interference counteraction method is used to counteract the remain interference between two diversity signals. This is done as follows:
  • a second iteration operation can be done by taking last result ⁇ circumflex over (d) ⁇ (1) and ⁇ circumflex over (d) ⁇ (2) of formula (8) in formula (10) and formula (11).
  • the obtained results of r 1 ′, r 2 ′, r 1 ′′ and r 2 ′′ are substituted to formula (8) again, and then formula (8) is recalculated to obtain a decoding result after the second iteration operation.
  • the iteration procedure can be done for M times, and this is the simplified joint detection algorithm.
  • the invention proposes a space-time encoding and decoding method that takes independent data field as a processing unit for encoding input, and this is different with the prior method that takes data symbols or a string of symbols as a processing unit.
  • a simplified decoding method is designed to obtain a better performance with small amount of calculation complexity.
  • the invention provides a simple and effective solution for space-time encoding and decoding on a frequency selective fading channel.

Abstract

A space-time encoding and decoding for a frequency selective fading channel. An encoder takes two independent data fields of a time slot in input data as a processing unit with space-time orthogonal encoding method, encodes them and generates two data vectors, and two diversity signals, and transmits them simultaneously, each through one diversity antenna. A receiving terminal neglects mutual interference between said two diversity signals caused by non-orthogonality, performing joint detection only taking into account affect to said two diversity signals from multipath interference and multi-user interference, obtaining a decoding result. Implementing interference counteraction based on result of joint diction to remove interference between the two diversity signals, and then returning to the previous step to implement iteration for decoding. An independent data field as a processing unit for encoding and decoding, and the decoding takes an iteration method based on joint detection and interference counteraction.

Description

    FIELD OF THE TECHNOLOGY
  • The invention relates to mobile communication technology, more particularly to a method of space-time encoding and decoding for a frequency selective fading channel.
  • BACKGROUND OF THE INVENTION
  • Space-time encoding is one of the important methods that can raise performance of a wireless communication system effectively. There are two branches of the space-time encoding, one is layered space-time encoding and the other is space-time encoding based on transmitting diversity. The space-time encoding based on transmitting diversity can be further divided into two kinds: space-time block encoding and space-time trellis encoding.
  • Along with the development of high-speed wireless communication technology, the signal transmission bandwidth and rate is increased continuously, which means that time for transmitting a data symbol is shorter and shorter. Therefore, time delay spread of a wireless transmission channel cannot be neglected, that is, the channel frequency selective fading is getting worse.
  • The prior space-time encoding and decoding schemes are designed based on a flat fading channel. When the schemes are used for a frequency selective fading channel, the performance becomes worse obviously, and it is too complex to implement when improving performance of the algorithm.
  • In a multi-user frequency selective fading channel, since Inter-Symbol Interference (ISI) and Multiple Access Interference (MAI) exist at the same time, implementation of space-time encoding and decoding has great difficulty. Some effective methods for counteracting ISI and MAI on a frequency selective channel, such as equalization, joint detection method etc., become very complex or even failure if space-time encoding is involved therein.
  • In the 3rd Generation Partnership Project—Time Division Duplex (3GPP-TDD) system, the prior space-time encoding and decoding scheme used for a multi-user frequency selective fading channel only performs space-time encoding for the basic common control channel, but in the 3rd Generation Partnership Project—Frequency Division Duplex (3GPP-FDD) system, space-time encoding is employed for most channels. The 3GPP-TDD space-time encoding scheme first takes a symbol as an encoding and decoding unit, later it takes a half of symbols of a data field as an encoding and decoding unit. Since these schemes have many changes that bring more complex compared with the schemes in which space-time encoding is not employed, the space-time transmission diversity (STTD) scheme is discarded in 3GPP-TDD v4.3 and space code transmission diversity (SCTD) scheme is applied. Although the reception processing procedure is simplified with the SCTD, more channel resource is occupied and more channels are employed; it is difficult to be applied to other kinds of channels, and also it is impossible to be applied on the multipath diversity situation.
  • There is a space-time encoding and decoding scheme that transforms high-speed data to multiple parallel low-speed data and transmits them on multiple channels, but really this is a space-time—orthogonal frequency division multiplexing (ST-OFDM) method that would thoroughly change the signal structure and system on the physical layer, so it is greatly limited in practical use.
  • In summary, the space-time encoding and decoding method is important to improve performance of a wireless communication system. Usually, a symbol or a string of symbols are used as a processing unit for encoding and decoding, but under the condition of a frequency selective fading channel, improvement of performance is limited by the calculation complexity.
  • SUMMARY OF THE INVENTION
  • An object of the invention is to design a space-time encoding and decoding method that is suitable to the frequency selective fading channel to obtain better performance with small amount of calculation complexity.
  • A space-time encoding and decoding method for a frequency selective fading channel according to the present invention comprises:
      • A. an encoder taking two independent data fields of a time slot in input data as a processing unit with space-time orthogonal encoding method, encoding them and generating two data vectors, thereby forming two diversity signals, and transmitting said two diversity signals simultaneously with each through one diversity antenna;
      • B. a terminal receiving said two diversity signals, and neglecting mutual interference between said two diversity signals caused by non-orthogonality;
      • C. said terminal performing joint detection only taking into account affect to said two diversity signals from multipath interference and multi-user interference, thereby obtaining a decoding result; and
      • D. implementing interference counteraction based on result of joint diction to remove interference between two diversity signals, and then returning to step C to implement iteration for decoding processing.
  • Two diversity signals in step A may be transmitted through two diversity beams of one smart antenna respectively and simultaneously.
  • The method may further comprise the step of predefining number of iteration times to determine execution times from step C to step D and from step D to step C again.
  • The method of the invention is a new space-time encoding and decoding method that is suitable to a frequency selective fading channel. The method takes an independent data field as a processing unit, and the decoding applies an iteration method based on joint detection and interference counteraction. When making joint detection, only affect to diversity signal from multipath interference and multi-user interference is taken into account, and then interference counteraction is implemented based on the joint detection result to remove interference between diversity signals.
  • With the space-time encoding and decoding scheme proposed in the invention, good performance can be reached with small amount of computation complexity in a frequency selective fading channel. The invention provides a simple and effective solution for space-time encoding and decoding on a frequency selective fading channel.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a schematic diagram illustrating a data structure for time-slot CDMA burst data.
  • FIG. 2 shows the input and output of a space-time encoder when taking a data field as a processing unit.
  • FIG. 3 is a flowchart illustrating the simplified decoding procedure of the invention.
  • DETAILED DESCRIPTION OF THE INVENTION
  • The invention will be described in more detail hereinafter with reference to the accompanying drawings.
  • In a frequency selective fading channel, the ISI exists between neighbor symbols. Therefore, in a general space-time encoding method, there is not only interference between diversity signals, but also interference between neighbor encoding units and interference between neighbor encoding blocks. If the interference were neglected, the communication performance would be worse; and if the interference were considered, the calculation complexity would be increased greatly.
  • An independent data block is taken as the processing unit in the encoding and decoding method according to the present invention, so the interference between neighbor encoding units and neighbor encoding blocks does not exist, which simplifies the signal detection and decoding processing. This processing method is similar or compatible to the processing methods in which space-time encoding processing is not employed to a great extent. Many processing schemes for counteracting ISI and MAI can be used in the space-time encoding situation with small amount of change.
  • FIG. 1 shows data structure of a time-slot CDMA burst data in the 3GPP-TDD system. It can be seen from FIG. 1 that in parallel K burst data of a multi-user or multi-channel, each time-slot includes two data fields (or referred as data blocks): DATA FIELD 1 and DATA FIELD 2, and there is a midamble between these two data fields. So these two data fields are independent and there is no mutual interference between them. The end of a time slot is a guard period (GP). Every data field has N symbols, and every symbol is consisted of Q chips.
  • In this invention, an independent data field is used as a processing unit for encoding, and at the receiving end the decoding also takes a data field as a processing unit. It is simple when this method is used in double diversity (theoretically it can be used in the multiple diversity, but the complexity is increased and therefore it is not practicable). Therefore, the encoding and decoding method according to the present invention can be employed with small amount of change for the signal structure and processing method. Furthermore, since the two data fields are independent, and there is no interference between them, the detection and decoding method can be simplified and improved, and better detection performance can be obtained with a small amount of calculation volume or a small quantity of iterative times.
  • FIG. 2 shows a space-time encoder 20 taking a data field as a processing unit. Input data of the encoder 20, i.e., information data vector d in a time slot, can be represented as d=[dT(1)dT(2)]T; wherein d(1) and d(2) are two independent data fields, and in a 3GPP-TDD system they can be two data fields in one time slot; T denotes a transpose operation. The data which has been encoded by the encoder 20 is [dT(1)dT(2)]T and [−d*T(2)d*T(1)]T, wherein * represents conjugate. The two generated data vectors can be transmitted simultaneously by two different conventional diversity antennas: diversity antenna 1 and diversity antenna 2, or by two different diversity beams of one smart antenna: smart antenna diversity beam 1 and smart antenna diversity beam 2. In other words, the diversity antenna 1 (or diversity beam 1) transmits data vector [dT(1)dT(2)]T and the diversity antenna 2 (or diversity beam 2) transmits data vector [−d*T(2)d*T(1)]T simultaneously, thereby the space-time encoding is realized. Specially, the input data [dT(1)dT(2)]T is encoded by conventional space-time diversity orthogonal encoding method, and two output data vectors: [dT(1)dT(2)]T and [−dT(2)d*T(1)]T are obtained and transmitted via two diversity antennas simultaneously and respectively.
  • In the following, the detection and decoding method for space-time encoding mode which takes a data field as a processing unit will be described, i.e. the detection and decoding scheme corresponding to the designed data field encoding scheme will be described. Here, it is called the original detection and decoding method.
  • Data corresponding to a data field can be expressed as the formula (1):
    d(i)=
    Figure US20060072680A1-20060406-P00900
    d 1 (l) , . . . , d 1 (K) ,d 2 (l) , . . . , d 2 (K) , . . . , d N (l) , . . . , d N (K)
    Figure US20060072680A1-20060406-P00901
    T  (1)
  • Wherein i is 1, 2; K is the number of terminal users working simultaneously; N is the number of symbols in a user data field.
  • Suppose r1 and r2 represent the sample values of two data fields received at the terminal, and there is no interference between r1 and r2 even on a frequency selective fading channel. The r1 and r2 can be expressed as the formula (2): { r 1 = A 1 d ( 1 ) - A 2 d * ( 2 ) + n 1 r 2 = A 2 d * ( 1 ) - A 1 d * ( 2 ) + n 2 ( 2 )
  • Wherein ni is the noise vector of the ith data field; Ai is the system matrix of the signal transmission between the ith transmitting antenna and receiving antenna, and the system matrix is determined by the channel pulse response and the user transmission waveform. The formula (2) can be rewritten as formula (3):
    r=Ad t +n  (3)
  • Wherein r=[r1 T,r2*T]T,dt=[dT(1)d*T(2)]T,n=[n1 T,n2*T]T, and A = [ A 1 - A 2 A 2 * A 1 * ] ( 4 )
  • From formula (4), it can be obtained that: A * T A = [ A 1 * T A 1 + ( A 2 * T A 2 ) * ( A 1 * T A 2 ) T - A 1 * T A 2 ( ( A 1 * T A 2 ) T - A 1 * T A 2 ) * T ( A 1 * T A 1 + ( A 2 * T A 2 ) * ) * ] ( 5 )
  • The matrix A is not an orthogonal matrix under the condition of frequency selective fading channel, so the performance will become worse if a match filter is applied. In order to obtain better performance, the optimized linear joint detection scheme is provided. The continuously estimated value {circumflex over (d)}t of the receiving data dt is:
    {circumflex over (d)} t=(B)−1 A* T r  (6)
  • Wherein (B)−1 has the function of interference suppression (implement inverse operation for B); A*Tr is the result of orthogonal match. The matrix B is shown in formula (7): B = { I MF A * T A ZF - BLE A * T A + σ 2 I MMSE - BLE ( 7 )
      • wherein σ2 is the noise power, and I is an identity matrix. The formula (7) shows three solutions among which MF represents matched filter scheme, ZF-BLE represents zero-forcing block equalization scheme and MMSE-BLE represents the minimum mean-square-error block equalization scheme.
  • The dimension of matrix B is 2NK×2NK, so the calculation complexity of formula (6) is far greater than that under the situation of no space-time encoding. Therefore, the object of simplifying processing and reducing calculation volume proposed in the invention cannot be realized with the original joint detection algorithm.
  • Based on the above-mentioned design, the invention provides a simplified decoding procedure having a characteristic of a small amount of calculation volume.
  • The simplified algorithm is an iterative algorithm. It is divided into two steps. In the first step, only multi-path interference and multi-user interference to every diversity signal is taken into account, and the upper right block of the formula (5) (
    Figure US20060072680A1-20060406-P00900
    A1*TA2
    Figure US20060072680A1-20060406-P00901
    T−A1*TA2) and the lower left block of the formula (5) (
    Figure US20060072680A1-20060406-P00902
    A1*TA2
    Figure US20060072680A1-20060406-P00903
    T−A1*TA2
    Figure US20060072680A1-20060406-P00903
    *T) are set to null, then the equation (6) is calculated. In the second step, interference is counteracted with the result of the first step to remove interference between diversity signals. The procedure can be done by multiple iterations.
  • FIG. 3 is a flowchart of the simplified decoding procedure of the invention.
  • Step 31, the terminal receives data.
  • Step 32, mutual interference between diversity signals caused by their non-orthogonality is neglected, upper right block and lower left block of formula (5) are set to be null (they are null under the condition of a flat fading channel).
  • Step 33, joint detection is performed, wherein only multipath interference and multi-user interference to every diversity signal is taken account, in this case formula (6) is simplified to formula (8) shown in the following: { d ( 1 ) = B S - 1 ( A 1 * T r 1 + ( A 2 * T r 2 ) * ) d ( 2 ) = B S - 1 ( A 1 * T r 2 + ( A 2 * T r 1 ) * ) ( 8 )
  • Formula (8) gives the result of simplified joint detection. The matrix BS in formula (8) is given by formula (9): B S = { I MF A 1 * T A 1 + ( A 2 * T A 2 ) * ZF - BLE A 1 * T A 1 + ( A 2 * T A 2 ) * + σ 2 I MMSE - BLE ( 9 )
  • Wherein σ2 is the noise power, and I is the identity matrix. Calculating matrix BS also has three ways: match filter MF, zero-forcing block equalization ZF-BLE and minimum mean-square-error block equalization MMSE−BLE.
  • The dimension of matrix BS is NK×NK, so the calculation complexity of formula (8) is far less than that of formula (6) and is similar to that under the situation of no space-time encoding.
  • Step 34, whether the number of iteration times is equal to or greater than the predefined number M is judged. Usually M is set at 1 or 2.
  • Step 35, when the number of iteration times is equal to or greater than the predefined number M, the calculation result of formula (8) is outputted as the decoding result directly.
  • Step 36, when the number of iteration times is less than the predefined number M, the calculation result of formula (8) is used to implement interference counteraction so as to remove interference between diversity signals, that is, an interference counteraction method is used to counteract the remain interference between two diversity signals. This is done as follows:
  • Affect of d(1) is subtracted from the received data signal to obtain a ‘clean’ signal as shown in formula (10): { r 1 = r 1 - A 1 d ( 1 ) r 2 = r 2 - A 2 d * ( 1 ) ( 10 )
    and affect of d(2) is subtracted from the received signal to obtain another ‘clean’ signal as shown in formula (11): { r 1 = r 1 + A 2 d * ( 2 ) r 2 = r 2 - A 1 d ( 2 ) . ( 11 )
  • Iteration operation is implemented. In detail, r1 and r2 in the second formula of formula (8) are respectively substituted with the result of the formula (10) r1′ and r2′; r1 and r2 in the first formula of formula (8) are respectively substituted with the result of the formula (11) r1″ and r2″; and then formula (8) is recalculated to obtain a decoding result after one iteration operation.
  • A second iteration operation can be done by taking last result {circumflex over (d)}(1) and {circumflex over (d)}(2) of formula (8) in formula (10) and formula (11). In other words, the obtained results of r1′, r2′, r1″ and r2″ are substituted to formula (8) again, and then formula (8) is recalculated to obtain a decoding result after the second iteration operation.
  • The iteration procedure can be done for M times, and this is the simplified joint detection algorithm.
  • Experience shows that usually only several iteration times, such as one to two times, are necessary to reach performance of the original joint detection algorithm. Therefore, the simplified joint detection algorithm according to this invention can obtain better performance with small amount of calculation complexity.
  • The invention proposes a space-time encoding and decoding method that takes independent data field as a processing unit for encoding input, and this is different with the prior method that takes data symbols or a string of symbols as a processing unit. With the proposed method, a simplified decoding method is designed to obtain a better performance with small amount of calculation complexity.
  • The invention provides a simple and effective solution for space-time encoding and decoding on a frequency selective fading channel.

Claims (6)

1. A space-time encoding and decoding method for a frequency selective fading channel, comprising:
A. an encoder taking two independent data fields of a time slot in input data as a processing unit with space-time orthogonal encoding method, encoding them and generating two data vectors, thereby forming two diversity signals, and transmitting said two diversity signals simultaneously with each through one diversity antenna;
B. a terminal receiving said two diversity signals, and neglecting mutual interference between said two diversity signals caused by non-orthogonality;
C. said terminal performing joint detection only taking into account affect to said two diversity signals from multipath interference and multi-user interference, thereby obtaining a decoding result; and
D. implementing interference counteraction based on result of joint diction to remove interference between two diversity signals, and then returning to step C to implement iteration for decoding processing.
2. The method of claim 1, wherein two diversity signals in step A are transmitted through two diversity beams of one smart antenna respectively and simultaneously.
3. The method of claim 1, further comprising the step of predefining number of iteration times to determine execution times from step C to step D and from step D to step C again.
4. The method of claim 1, wherein step B comprises: setting the upper right block and the lower left block of matrix
A * T A = [ A 1 * T A 1 + ( A 2 * T A 2 ) * ( A 1 * T A 2 ) T - A 1 * T A 2 ( ( A 1 * T A 2 ) T - A 1 * T A 2 ) * T ( A 1 * T A 1 + ( A 2 * T A 2 ) * ) * ]
to be null matrixes, and then calculating equation {circumflex over (d)}t=(B)−1A*Tr to obtain a simplified equation for joint detection; wherein A1 and A2 are system matrixes of signal transmission between first and second transmitting antennas and receiving antennas; A and B are matrixes; {circumflex over (d)}t is a value of continuous estimation of a receiving data field; r is a sample value of said receiving data field; T denotes a transpose operation; * denotes conjugate;
said joint detection in step C is calculated based on a simplified joint detection equation:
{ d ^ ( 1 ) = B S - 1 ( A 1 * T r 1 + ( A 2 * T r 2 ) * ) d ^ ( 2 ) = B S - 1 ( A 1 * T r 2 - ( A 2 * T r 1 ) * ) ,
wherein {circumflex over (d)}(1) and {circumflex over (d)}(2) are values of continuous estimation of two receiving data fields, BS is a matrix; r1 and r2 are sample values of two receiving data fields;
the step of implementing interference counteraction based on result of joint diction in step D further comprising:
D1. subtracting affect of a data field d(1) from received data signal based on the following formula,
{ r 1 = r 1 - A 1 d ( 1 ) r 2 = r 2 - A 2 d * ( 1 )
thereby obtaining r1′ and r2′; subtracting affect of another data field d(2) from received data signal based on the following formula:
{ r 1 = r 1 + A 2 d * ( 2 ) r 2 = r 2 - A 1 d ( 2 )
thereby obtaining r1″ and r2″;
D2. substituting r1′ and r2′ for r1 and r2 in the second equation of said simplified joint detection formula used in step C, and substituting r1″ and r2″ for r1 and r2 in the first equation of said simplified joint detection formula used in step C, calculating said simplified joint detection formula, thereby obtaining iteration results of {circumflex over (d)}(1) and {circumflex over (d)}(2).
5. The method of claim 4, wherein said matrix B is calculated by one of the following formulas:
B = { I A * T A A * T A + σ 2 I
these formulas including match filter scheme, zero-forcing block equalization scheme and minimum mean-square-error block equalization scheme; wherein σ2 is noise power, and I is an identity matrix;
said matrix BS is calculated by one of the following formulas:
B S = { I A 1 * T A 1 + ( A 2 * T A 2 ) * A 1 * T A 1 + ( A 2 * T A 2 ) * + σ 2 I
these formulas including match filter scheme, zero-forcing block equalization scheme and minimum mean-square-error block equalization scheme; wherein σ2 is noise power, and I is an identity matrix.
6. The method of claim 4, wherein said system matrixes A1 and A2 are determined by channel pulse response and user transmission waveform.
US10/518,426 2002-06-20 2003-06-02 Method of space-time encoding and decoding for frequency selective fading channel Active 2025-02-01 US7606318B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
CN02121410.7 2002-06-20
CNB021214107A CN1170374C (en) 2002-06-20 2002-06-20 Space-time compilation code method suitable for frequency selective fading channels
PCT/CN2003/000425 WO2004002036A1 (en) 2002-06-20 2003-06-02 Space-time coding/decoding method for frequency selective fading channel

Publications (2)

Publication Number Publication Date
US20060072680A1 true US20060072680A1 (en) 2006-04-06
US7606318B2 US7606318B2 (en) 2009-10-20

Family

ID=27811317

Family Applications (1)

Application Number Title Priority Date Filing Date
US10/518,426 Active 2025-02-01 US7606318B2 (en) 2002-06-20 2003-06-02 Method of space-time encoding and decoding for frequency selective fading channel

Country Status (8)

Country Link
US (1) US7606318B2 (en)
EP (1) EP1533928B1 (en)
JP (1) JP4267571B2 (en)
KR (1) KR100630917B1 (en)
CN (1) CN1170374C (en)
AT (1) ATE532282T1 (en)
AU (1) AU2003242195A1 (en)
WO (1) WO2004002036A1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040001465A1 (en) * 2002-06-28 2004-01-01 Interdigital Technology Corporation CDMA system transmission matrix coefficient calculation
CN103647591A (en) * 2013-12-27 2014-03-19 中国电子科技集团公司第五十四研究所 Cooperative interference detection method based on support vector machine
CN105763288A (en) * 2014-12-16 2016-07-13 电信科学技术研究院 Multi-user coding mode configuring and determining method and equipment based on code superposing
EP3282613A4 (en) * 2015-04-07 2018-04-18 China Academy of Telecommunications Technology Data sending method, receiving method and apparatus

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100452928C (en) * 2003-12-25 2009-01-14 西安电子科技大学 Coding method for mixed recursion lattice space-time code
CN100401646C (en) * 2004-09-24 2008-07-09 大唐移动通信设备有限公司 Multi region combined detection method of time gap code division multi address system
CN1953343B (en) * 2005-10-18 2010-12-08 大唐移动通信设备有限公司 A method to check soft bit of output generated channel encoder by linear joint detection
KR101241881B1 (en) * 2005-10-26 2013-03-11 엘지전자 주식회사 Method for encoding space-time codes in multi-antenna system
CN100369403C (en) * 2006-02-20 2008-02-13 东南大学 Parallel realizing method accepted by iterative detection decoding of wireless communication system
CN100442062C (en) * 2006-04-18 2008-12-10 大唐移动通信设备有限公司 Method for implementing iterative detection in multiple-input multiple-output system and multi-antenna detector
CN101123594B (en) * 2006-08-08 2012-07-25 上海贝尔阿尔卡特股份有限公司 System, device and method for MIMO base band processing
KR100829560B1 (en) 2006-08-09 2008-05-14 삼성전자주식회사 Method and apparatus for encoding/decoding multi-channel audio signal, Method and apparatus for decoding downmixed singal to 2 channel signal
CN101378284B (en) * 2007-08-29 2013-02-27 中兴通讯股份有限公司 Method for implementing control channel transmission diversity and corresponding signal transmission device
CN101399803B (en) * 2007-09-27 2011-04-13 大唐移动通信设备有限公司 Multi-user detection method and device for OFDM signal
CN101606368A (en) * 2007-12-21 2009-12-16 联发科技股份有限公司 Decoding communication signals
CN101494488B (en) * 2008-01-23 2013-06-05 电信科学技术研究院 Method and apparatus for transmitting data through polarization antenna
JP2018207333A (en) * 2017-06-06 2018-12-27 富士通株式会社 Base station, radio terminal, radio communication system, and communication control method

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6185258B1 (en) * 1997-09-16 2001-02-06 At&T Wireless Services Inc. Transmitter diversity technique for wireless communications
US20020003774A1 (en) * 2000-07-05 2002-01-10 Zhaocheng Wang Pilot pattern design for a STTD scheme in an OFDM system
US6356605B1 (en) * 1998-10-07 2002-03-12 Texas Instruments Incorporated Frame synchronization in space time block coded transmit antenna diversity for WCDMA
US6549585B2 (en) * 1997-10-06 2003-04-15 At&T Corp Combined interference cancellation and maximum likelihood decoding of space-time block codes
US20040052315A1 (en) * 2000-10-03 2004-03-18 Jorn Thielecke Multi strata system
US6775260B1 (en) * 1999-02-25 2004-08-10 Texas Instruments Incorporated Space time transmit diversity for TDD/WCDMA systems
US6865373B2 (en) * 2001-05-21 2005-03-08 Nortel Networks Limited Apparatus and method for encoding and decoding data within wireless networks
US6898248B1 (en) * 1999-07-12 2005-05-24 Hughes Electronics Corporation System employing threaded space-time architecture for transporting symbols and receivers for multi-user detection and decoding of symbols
US6959047B1 (en) * 2001-04-09 2005-10-25 At&T Corp Training-based channel estimation for multiple-antennas
US7154964B1 (en) * 2001-04-09 2006-12-26 At&T Corp. Creating training sequences for space-time diversity arrangements
US7181244B2 (en) * 2000-11-16 2007-02-20 Qualcomm, Incorporated Method and apparatus for using position location to direct narrow beam antennas
US7215718B1 (en) * 1999-04-28 2007-05-08 At&T Corp. Combined channel coding and space-time block coding in a multi-antenna arrangement
US7272192B2 (en) * 2000-04-14 2007-09-18 Board Of Trustees Of The Leland Stanford Junior University Time-reversal block transmit diversity system for channels with intersymbol interference and method

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1133071B1 (en) * 1999-02-25 2014-05-21 Texas Instruments Incorporated Space time transmit diversity for tdd/wcdma systems
EP1069707A1 (en) * 1999-07-13 2001-01-17 Motorola, Inc. Transmit diversity transmitter and receiver for radio communications systems
JP2001267982A (en) * 2000-03-22 2001-09-28 Matsushita Electric Ind Co Ltd Sttd encoding method and diversity transmitter
KR100355266B1 (en) * 2000-09-29 2002-10-11 한국전자통신연구원 STTD Decoding Demodulator Applicable To Spread Spectrum Communication

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6185258B1 (en) * 1997-09-16 2001-02-06 At&T Wireless Services Inc. Transmitter diversity technique for wireless communications
US6549585B2 (en) * 1997-10-06 2003-04-15 At&T Corp Combined interference cancellation and maximum likelihood decoding of space-time block codes
US6356605B1 (en) * 1998-10-07 2002-03-12 Texas Instruments Incorporated Frame synchronization in space time block coded transmit antenna diversity for WCDMA
US6775260B1 (en) * 1999-02-25 2004-08-10 Texas Instruments Incorporated Space time transmit diversity for TDD/WCDMA systems
US7215718B1 (en) * 1999-04-28 2007-05-08 At&T Corp. Combined channel coding and space-time block coding in a multi-antenna arrangement
US6898248B1 (en) * 1999-07-12 2005-05-24 Hughes Electronics Corporation System employing threaded space-time architecture for transporting symbols and receivers for multi-user detection and decoding of symbols
US7272192B2 (en) * 2000-04-14 2007-09-18 Board Of Trustees Of The Leland Stanford Junior University Time-reversal block transmit diversity system for channels with intersymbol interference and method
US20020003774A1 (en) * 2000-07-05 2002-01-10 Zhaocheng Wang Pilot pattern design for a STTD scheme in an OFDM system
US7221645B2 (en) * 2000-07-05 2007-05-22 Sony Deutschland Gmbh Pilot pattern design for a STTD scheme in an OFDM system
US20040052315A1 (en) * 2000-10-03 2004-03-18 Jorn Thielecke Multi strata system
US7181244B2 (en) * 2000-11-16 2007-02-20 Qualcomm, Incorporated Method and apparatus for using position location to direct narrow beam antennas
US7154964B1 (en) * 2001-04-09 2006-12-26 At&T Corp. Creating training sequences for space-time diversity arrangements
US6959047B1 (en) * 2001-04-09 2005-10-25 At&T Corp Training-based channel estimation for multiple-antennas
US6865373B2 (en) * 2001-05-21 2005-03-08 Nortel Networks Limited Apparatus and method for encoding and decoding data within wireless networks

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040001465A1 (en) * 2002-06-28 2004-01-01 Interdigital Technology Corporation CDMA system transmission matrix coefficient calculation
US7203181B2 (en) * 2002-06-28 2007-04-10 Interdigital Technology Corporation CDMA system transmission matrix coefficient calculation
US20070189238A1 (en) * 2002-06-28 2007-08-16 Interdigital Technology Corporation CDMA system transmission matrix coefficient calculation
US7693113B2 (en) 2002-06-28 2010-04-06 Interdigital Technology Corporation CDMA system transmission matrix coefficient calculation
CN103647591A (en) * 2013-12-27 2014-03-19 中国电子科技集团公司第五十四研究所 Cooperative interference detection method based on support vector machine
CN105763288A (en) * 2014-12-16 2016-07-13 电信科学技术研究院 Multi-user coding mode configuring and determining method and equipment based on code superposing
EP3236634A4 (en) * 2014-12-16 2018-01-03 China Academy of Telecommunications Technology Configuration method, determination method and device of multiuser encoding method based on encoding superimposition
US10382108B2 (en) 2014-12-16 2019-08-13 China Academy Of Telecommunications Technology Method and device for configuring and determining code superposition-based multiuser encoding mode
EP3282613A4 (en) * 2015-04-07 2018-04-18 China Academy of Telecommunications Technology Data sending method, receiving method and apparatus
US10230445B2 (en) 2015-04-07 2019-03-12 China Academy Of Telecommunications Technology Data transmission method, data reception method, data transmission device and data reception device

Also Published As

Publication number Publication date
KR20060055274A (en) 2006-05-23
WO2004002036A8 (en) 2005-02-10
AU2003242195A1 (en) 2004-01-06
JP2005530434A (en) 2005-10-06
CN1170374C (en) 2004-10-06
CN1446005A (en) 2003-10-01
AU2003242195A8 (en) 2004-01-06
JP4267571B2 (en) 2009-05-27
ATE532282T1 (en) 2011-11-15
EP1533928A4 (en) 2008-06-04
US7606318B2 (en) 2009-10-20
KR100630917B1 (en) 2006-10-02
EP1533928A1 (en) 2005-05-25
EP1533928B1 (en) 2011-11-02
WO2004002036A1 (en) 2003-12-31

Similar Documents

Publication Publication Date Title
US7796678B2 (en) Communication system with receivers employing generalized two-stage data estimation
EP1779537B1 (en) Reduced complexity soft value generation for mimo jd-grake receivers
US7606318B2 (en) Method of space-time encoding and decoding for frequency selective fading channel
US8290084B2 (en) Space time transmit diversity for TDD/WCDMA systems
Bhashyam et al. Multiuser channel estimation and tracking for long-code CDMA systems
US20070280336A1 (en) Constrained Optimization Based Mimo Lmmse-Sic Receiver for Cdma Downlink
US6466611B1 (en) Multi-user detection using a finite-impulse-response matrix filter
EP1619807B1 (en) Chip equalizer for spread spectrum receiver
CN101573887A (en) Data equalisation in a communication receiver with transmit and receive diversity
US7486750B1 (en) Method for obtaining information regarding interference in the receiver of a message transmission system
EP1133071B1 (en) Space time transmit diversity for tdd/wcdma systems
US7415065B2 (en) Adaptive filtering in the presence of multipath
JP5077578B2 (en) Receiving machine
Li et al. Transmit diversity and linear and decision-feedback equalizations for frequency-selective fading channels
Irmer et al. Nonlinear chip-level multiuser transmission for TDD-CDMA with frequency-selective MIMO channels
Chan et al. A reduced-rank MMSE-DFE receiver for space-time coded DS-CDMA systems
Marzook et al. Reduced rank technique for joint channel estimation and joint data detection in TD-SCDMA systems
Lai et al. BER performance of STBC over frequency selective fading channels in the downlink WCDMA system
Wang et al. Joint detection for space-time block-coded TD-CDMA systems
Cagley et al. Performance of ML rate determination for an IS-95 downlink SIC receiver
Yue et al. Space-time coded CDMA: blind equalization and multiuser detection
Sud A Rank Prediction Method for the Multistage Wiener Filter used for Interference Mitigation in CDMA Systems
Hombs et al. Combining space-time codes and interference suppression in asynchronous DS-CDMA

Legal Events

Date Code Title Description
AS Assignment

Owner name: DA TANG MOBILE COMMUNICATIONS EQUIPMENT CO., LTD.,

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:WANG, YINGMIN;RAN, XIAOLONG;REEL/FRAME:016657/0755;SIGNING DATES FROM 20050218 TO 20050220

STCF Information on status: patent grant

Free format text: PATENTED CASE

FPAY Fee payment

Year of fee payment: 4

FPAY Fee payment

Year of fee payment: 8

MAFP Maintenance fee payment

Free format text: PAYMENT OF MAINTENANCE FEE, 12TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1553); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

Year of fee payment: 12

AS Assignment

Owner name: DATANG MOBILE COMMUNICATIONS EQUIPMENT CO., LTD., CHINA

Free format text: CHANGE OF NAME;ASSIGNOR:CHINA ACADEMY OF TELECOMMUNICATIONS TECHNOLOGY;REEL/FRAME:056804/0182

Effective date: 20210609